Attrition-mill.



E. P. ALSTED.

ATTRITION MILL.

APPLICATION FILED APR. 3,1909.

Patenfied June 28, 1910.

H7 TORNEYS.

UNITED STATES PATENT OFFICE.

EDWARD P. ALSTED, OF TRUESDELL, WISCONSIN.

ATTRITION-MILL.

I '0 all whom it may concern:

Be it known that I, EDWARD P. ALsTED, residing in Truesdell, in thecounty of Kenosha and State of Wisconsin, have invented new and usefulImprovements in Attrition- Mills, of which the following is adescription, reference being had to the accompanying drawings, which area part of this specification.

This invention relates to improvements in attrition mills and moreparticularly to the form of mill in which the grinding is effected bymeans of two opposite disks rotating in opposite directions and providedon their working faces with opposing grinding plates not in contact witheach other, the plates being provided with pockets and ribs whereby thegrain fed between the plates is reduced by attrition.

One of the objects of this invention is to provide grinding disk platesfor attrition mills in which the material being reduced between theplates is evenly distributed throughout the entire grinding surfaces ofthe plates thereby preventing the material from being movedcentrifugally to the grinding surfaces near the outer periphery of thedisk and causing uneven and eX- cessive wear of the grinding surfaces atthis point.

Another object of this invention is to provide grinding disk plates forattrition mills in which the pockets or recesses formed in said platesare so positioned with relation to the pockets or recesses formed in theopposing disk that material may freely pass radially from one series ofpockets to another series.

Vith the above, and other objects in view, the invention consists of thedevice and its parts and combinations, and all equivalents thereof.

In the accompanying drawing in which the same reference charactersindicate the same parts in the several views; Figure 1 is a face view ofa fragment of a grinding disk provided with the improved grindingplates; Fig. 2 is a face view on a reduced scale of the complete diskprovided with the grind-' ing plates; Fig. 3 is a transverse section ofone of the plates taken on line 33 of Fig. 1; and Fig. at is adiagrammatic view of one of the ribs of each opposing disk showing theline of engagement of the material re- Specification of Letters Patent.Patented Jung 28 1910,

Application filed April 3, 1909.

Serial No. 487,756.

ducing edges, one of the ribs being shown by dotted lines.

Referring to the drawing the numeral 5 indicates one of a plurality ofsegmental grinding plates which are adapted to be fastened to theopposing heads or disks of the attrition mill by means of screws 6passing through openings provided in said plates and threaded to thedisks. The segmental plates are provided with radial ribs 7 an outerconcentric rib 8 and an inner segmental eccentric rib 9 forming recessesor pockets 10 in the plates. The inner concentric edges 11 of the platesare beveled off to more freely admit the material to be ground into thepockets between the plates attached to the opposing heads, and theradial ribs start or project from the fiat portion of the plates at andnear the point where the beveled edge merges with said flat portion,each alternate radial rib being somewhat shorter than the adjacentradial ribs. While the ribs eX- tend in substantially radial lines fromthe axis of the disks the cutting or working edges 12 of the ribs extendin tangential lines of different angles from a small circle concentricwith said axis.

The inner ends of the ribs are of a certain width indicated by thenumeral 13 and the side edges of the ribs gradually converge toward eachother to a point 14. From this point the sides edges of the ribsgradually diverge to a point where the rib merges with the innersegmental eccentric rib 9. From the outer edge of the segmentaleccentric rib the edges of the radial ribs, reduced in width extend indiverging lines to the concentric rib 8 and merges therewith thusproviding cutting edges, which, when the two opposing disks rotating inopposite directions are reducing the material fed therebetween the outerportions of the cutting edges forming the outer pockets will engage thematerial in said outer pockets first and the line of engagement willtravel, as the rotation continues, toward the inner eccentric rib, andthe material within the inner line of pockets will be engaged by theopposite end portions of the ribs forming said pockets and the line ofengagement will travel toward the portions of the ribs which are reducedin width and as indicated by the numeral 14, thus providing for the evenwear of the cutting edges of the plates. It is of course understood thatthe material being reduced between the attrition faces of the plates isfed to said plates from the inner portion thereof, and is movedoutwardly therefrom by centrifugal force.

It will be noticed that the inner rib of each segmental plate extends ina curve of larger diameter than the curve of the plate, or in otherwords the rib is eccentric to the path of travel of the segment, andwhen the plates are assembled on the disks or heads of the attritionmill the ends of the eccentric ribs meet and form a hexagonal shaped ribwith corners l5 and curved sides 16. The hexagon shaped rib ispositioned concentric to the axis of the disks, and when the plates ofopposing disks are rotated the corners of the hexagonal ribs willoverlap the curved sides of the ribs of the opposite plates and opencommunication between the inner and the outer series of pockets so thatmaterial being reduced therebetween may pass from the inner to the outerpockets. The hex agonal ribs of the opposing plates also serve to assistin reducing the material. As the corners pass the curved sides they forma cutting edge similar to the radial ribs.

Both side edges of the radial ribs are similar in shape so that when theedges on one side are worn the disks may be rotated in the oppositedirection and the same results obtained.

From the foregoing description it will be seen that provision is madefor spreading the wear of the cutting or reducing edges of the grindingplates throughout the entire plate and thus eliminating excessive wearat one point of each reducing edge.

lVhat I claim as my invent-ion is:

1. An attrition mill, comprising opposite rotatable plates provided withmaterial reducing ribs, the material engaging edges of ribs of oppositeplates diverging toward the axis of the plates when in engagement witheach other to advance the line of ma terial of said edges in a directiontoward the axis of rotation, and segmentally curved ribs provided onsaid plates, the segmental curvatures of which are eccentric to the axisof rotation.

2. An attrition mill, comprising opposite rotatable plates provided withmaterial reducing ribs, the material engaging edges of ribs of oppositeplates diverging toward the axis of the plates when in engagement witheach other to advance the line of material engagement of said edges in adirection toward the axis of rotation, ribs concentric to the axis ofrotation connected to the outer ends of said ribs, and segmentallycurved ribs provided on said plates, the segmental curvatures of Whichare eccentric to the axis of rotation.

3. A grinding plate for attrition mills, comprising a segmental plateprovided with radial ribs, the material engaging edges of adjacent ribsdiverging from each other toward their inner ends, and a transverse ribformed on said plate and extending in a line eccentric to the axis ofsaid plate.

4. A grinding plate for attrition mills, comprising a segmental plateprovided with radial ribs, the material reducing edges of adjacent ribsdiverging from each other for a portion of their lengths then convergetoward each other for a certain distance and then again convergingtoward each other toward their outer ends, and a rib extendingtransversely across the radial ribs in a line eccentric to the axis ofsaid plate.

5. A grinding plate for attrition mills, comprising a segmental plateprovided with radial ribs, the material reducing edges of adjacent ribsdiverging from each other for a portion of their lengths then convergingtoward each other for a certain distance and then again convergingtoward each other toward their outer ends, a rib extending transverselyacross the radial ribs in a line eccentric to the axis of said plate,and an outer annular rib extending in a line concentric to the axis ofsaid plate.

6. An attrition mill, comprising opposite rotatable plates provided withmaterial engaging ribs forming pockets, the edges of adjacent ribsdiverging toward the axis of rotation of the plates, and annular ribsformed on said plates and provided with a plurality of segmental sideswhich are positioned to overlap portions of the annular rib of theopposite plate and permit material to pass radially from one pocket toanother pocket.

7. A grinding plate for attrition mills, comprising a segmental platehaving an inner beveled edge and provided with radial ribs, the materialengaging edges of ad j acent ribs converging toward each other towardtheir outer ends, and a transverse rib formed on said plate andextending in a line eccentric to the axis of said plate.

In testimony whereof, I aflix my signature, in presence of twowitnesses.

EDXVARD P. ALSTED.

/Vitnesses:

R. S. G. CALDWELL, ALMA A. KLUG.

